Display member

ABSTRACT

Provided is a display member containing: an display layer which exhibits a structural color and contains spherical bodies and a matrix; and a reflective interface which reflects a light transmitting through the display layer, wherein the reflective interface is made between the display layer and a reflective interface forming layer which is provided in contact with the display layer; and a refractive index of the spherical bodies na, a refractive index of the matrix nb and a refractive index of the reflective interface forming layer nc satisfy the following Formulas (1) and (2):
 
0.35&lt; nc/na &lt;1.00,  Formula (1)
 
0.35&lt; nc/nb &lt;1.00.  Formula (2)

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2008-069700filed on Mar. 18, 2008 with Japan Patent Office, the entire content ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a display member which exhibits astructural color.

2. Background

Heretofore, there have been proposed several kinds of display membersused for a sensor, a display, a panel, a ravel and a sheet which makeuse of specific properties of a structural color. Examples thereofinclude display members containing solid particles arranged in aperiodic structure and filled with a gas, a liquid or a solid materialbetween the solid particles. (Refer to Patent documents 1 and 2.)

However, in recent years, there is a demand of a display having a highanisotropy in visibility which permits only the user of the display toobserve the display from the viewpoint of security. The display membersdisclosed in the above-described patent documents have a problem to bevisible regardless of the observing directions.

-   Patent Document 1: Japanese Patent Application Publication (JP-A)    No. 2004-269922-   Patent Document 1: JP-A No. 2006-28202

SUMMARY

The present invention is achieved in consideration of the aboveproblems. An object of the present invention is to provide a displaymember provided with a security property.

One of the embodiments of the present invention is a display membercomprising:

a display layer which contains spherical bodies and a matrix, andexhibits a structural color; and

a reflective interface which reflects a light transmitting through thedisplay layer,

wherein the reflective interface is made of a reflective interfaceforming layer which is provided in contact with the display layer; and

a refractive index of the spherical bodies na, a refractive index of thematrix nb and a refractive index of the reflective interface forminglayer nc satisfy the following Formulas (1) and (2):0.35<nc/na<1.00  Formula (1)0.35<nc/nb<1.00.  Formula (2)

Another embodiment of the present invention is a display membercomprising:

a display layer which contains spherical bodies and a matrix, andexhibits a structural color; and

a reflective interface which reflects a light transmitting through thedisplay layer,

wherein the reflective interface is made of a reflective interfaceforming upper layer and a reflective interface forming under layer,provided that the upper layer is nearer to the display layer than theunder layer, and the under layer is provided in contact with the upperlayer; and

a refractive index of the matrix nb, and a refractive index of thereflective interface forming upper layer nc1 and a refractive index ofthe reflective interface forming under layer nc2 satisfy the followingFormulas (3) and (4):nb≦nc1  Formula (3)0.35<nc2/nc1<1.00.  Formula (4)

In a display member of the present invention, the incident light comingfrom above the display layer is usually selectively reflected at adisplay layer. The reflected light has a wavelength determined by anangle θ which is determined with respect to a perpendicular line of thedisplay member, which is called as “viewing angle”, and exhibits astructural color. This reflected light having a specific wavelength iscalled as “a display layer selective-reflected light”. Due to thedisplay structure in which a specific reflective interface is formedunder the display layer, among the lights which transmit though thedisplay layer, a light having a specific wavelength based on theproperty of the reflective interface, which is called as “an interfacereflected light”, is selectively reflected. The interface reflectedlight transmits again through the display layer. The structural color isexhibited by both “a display layer selective-reflected light” and “theinterface reflected light”.

On the other hand, in the display member of the present invention, whenthe incident light arriving at the reflective interface becomes fullyinterface reflected light, which means when the incident light iscompletely reflected, the observer cannot recognize an exhibition of astructural color.

And, according to the display member of the present invention, theabove-described interface reflected light is controlled by the propertyof the specific reflective interface. As a result, the range of theobservable angle which permits exhibition of a structural color issuitably determined. Consequently, the angle dependency, in which theexhibition of the structural color is prohibited for a large viewingangle, is realized resulting in achieving a display member of highsecurity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory cross-sectional view illustrating an example ofa constitution of a display member of the present invention.

FIG. 2 is an explanatory cross-sectional view illustrating an example ofa constitution of a display layer in an display member of the presentinvention.

FIG. 3 is an explanatory cross-sectional view illustrating anotherexample of a constitution of a display member of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is explained in detail below.

First Embodiment

A display member of a first embodiment according to the presentinvention has a structure as illustrated by FIG. 1. It has a displaylayer 10 exhibiting a structural color; and a reflective interface S1produced by the display layer 10 and a reflective interface forminglayer 11 which is provided in contact with the display layer 10. Thereflective interface S1 reflects the light which transmits through thedisplay layer 10. When a refractive index of the spherical bodies whichform the display layer 10 is na, a refractive index of a matrix M whichforms the display layer 10 is nb and a refractive index of thereflective interface forming layer 11 is nc, the display member of thepresent invention satisfies the following Formulas (1) and (2):0.35<nc/na<1.00  Formula (1)0.35<nc/nb<1.00.  Formula (2)

When the display member satisfies the above-described Formulas (1) and(2) a light having an expected wavelength is each respectivelyselectively reflected at a portion of a contact region S1 a which isformed by a spherical body 12 contacting with a reflective interface S1and a reflective interface forming layer 11, and at a portion of acontact region S1 b which is formed by a matrix M contacting with areflective interface S1 and a reflective interface forming layer 11. Asa result, the light having an expected wavelength is selectivelyreflected at all region of the reflective interface S1.

In such display member, a structural color is exhibited by mixed lightsof: (i) an interface reflected light which is selectively reflected atthe reflective interface S1; and (ii) a display layerselective-reflected light which is produced by the display layer 10.

And, in this display member, when the viewing angle is larger than anexpected value, the interface reflected light selectively reflected atthe reflective interface S1 is designed to become all of the lightentered in the reflective interface S1. This means the total reflectionis realized at the reflective interface S1. As a result, all of thetotal light entered in the display member is reflected either by thedisplay layer 10 or the reflective interface S1. Namely, due to the factthat all of the light entered in the display member is reflected,exhibition of a structural color is prohibited at a viewing angle largerthan an expected value.

In the display member of the present invention, the range of observableangle in which a structural color can be recognized varies depending onthe combination of the materials which form each of the spherical bodies12, the matrix M and the reflective interface forming layer 11. Anexample of a preferred range of a viewing angle is from 0 to 70°, andanother example of a more preferred range is from 0 to 55°. A preferredupper side value of a viewing angle range may be more than 20°.

A particular example of a viewing angle is determined to be from 0 to52°, when a refractive index of the spherical bodies 12 is 1.56, arefractive index of the matrix M is 1.41, and a refractive index of areflective interface forming layer 11 is 1.34.

The ratios of the refractive indexes nc/na and nc/na in Formulas (1) and(2) indicate the conditions under which the total reflection is realizedat the reflective interface S1. In particular, nc/na is a conditionwhich produces the total reflection at an interface (a contact region S1a) between the spherical bodies 12 and the reflective interface forminglayer 11; and nc/nb is a condition which produces the total reflectionat an interface (a contact region S1 b) between the matrix M and thereflective interface forming layer 11.

When a ratio of a refractive index nc of a reflective interface forminglayer 11 to a refractive index na of spherical bodies 12, nc/na(hereafter it is called as “a refractive index ratio at a contact regionS1 a”) is 0.35 or less, and/or a ratio of a refractive index nc of areflective interface forming layer 11 to a refractive index nb of amatrix M, nc/nb (hereafter it is called as “a refractive index ratio ata contact region S1 b”) is 0.35 or less, the range of observable anglebecomes too small to view to practical use. On the other hand, when therefractive index ratio nc/na at a contact region S1 a is 1.00 or more,and/or the refractive index ratio nc/nb at a contact region S1 b is 1.00or more, the incident light entered in the reflective interface S1cannot totally transmits through the reflective interface forming layer11 to produce an interface reflected light. As a result, a structuralcolor is exhibited only by a display layer selective-reflected light. Inthis case, there is no range of angle in which a structural color is notrecognized and the obtained display member cannot achieve an expectedsecurity property.

[Display Member]

The display layer 10 of the display member is composed of a periodicstructure 16 formed in a matrix M. Formation of such a periodicstructure in the display layer 10 makes it possible to recognize achromatic color by irradiation with a light in a visible range.

The display layer 10 has a regularly arranged structure as is shown inFIG. 1 in which spherical bodies 12 made of solid particles areregularly arranged in contact with each other in a matrix M in planedirection so as to form a spherical body layer 15. In the spherical bodylayer 15, the spherical bodies 12 are regularly arranged to be in astate of contact with each other in a depth direction.

Moreover, the display layer may have a regularly arranged structure asis shown in FIG. 2, a display layer 10A. In which, spherical bodies 12made of solid particles are regularly arranged in non-contact with eachother in a matrix M in plane direction to form a spherical body layer15. And in the spherical body layer 15, the spherical bodies 12 areregularly arranged to be in a state of non-contact with each other in adepth direction.

The spherical body layer 15 has a structure in which the sphericalbodies 12 are regularly arranged to be located in one direction withrespect to a direction of an incident light. In particular, it ispreferable that the spherical body layer 15 will form a closest packedstructure with the spherical bodies 12.

In display layer 10 an absolute value of a difference between arefractive index of the spherical bodies 12 and the matrix M (hereafterit is called as “a refractive index difference”) is preferably from 0.02to 2.0, and it is more preferably from 0.1 to 1.6.

When this refractive index difference is less than 0.02, the structuralcolor is hard to be realized. And, when this refractive index differenceis more than 0.02, the light scattering will be large and the obtainedstructural color becomes clouded to yield white turbidity.

[Structural Color]

The structural color obtained by the display member of the presentinvention is a color exhibited with mixed wavelength lights of aninterface reflected light which is selectively reflected at a reflectiveinterface S1 and a display layer selective-reflected light which isproduced by a display layer 10.

The display layer selective-reflected light concerned with the displaylayer 10 is a light represented by the following Scheme (1) based onBragg's Law and Snell's Law.λ=2nD(cos θ)  Scheme (1):

In Scheme (1), λ represents a peak wavelength of the structural color, nrepresents a refractive index of the display layer 10 represented byScheme (2) below, D represents a distance between the spherical bodylayers 15, and θ represents a viewing angle to a perpendicular line ofthe display member.n={na·c}+{nb·(1−c)}  Scheme (2):

In Scheme (2), na represents a refractive index of the spherical bodies12, nb represents a refractive index of the matrix M, and c represents avolume fraction of the spherical bodies 12 in the display layer 10.

Here, the peak wavelength of the structural color λ can be measuredusing MCPD-3700 (made of OTSUKA DENSHI Corporation Ltd.) which allow toconfirm the relationship between the light source and the viewing angleby making use of a glass fiber.

The particle layer distance D can be calculated from the measured peakwavelength of the structural color λ by using the above-described Scheme(1).

The thickness of the display layer 10 will varies depending on thepurpose of use. An example of the thickness is 0.1 to 100 μm.

A preferable example of the thickness of the spherical body layer 15 isfrom 0.1 to 100 μm.

When the thickness of the spherical body layer is less than 0.1 μm, thedensity of the obtained structural color maybe pale. On the other hand,when the thickness of the spherical body layer is more than 100 μm, thelight scattering may become so considerable that the structural colorwill become clouded.

In the display layer 10, the repeating number of the spherical bodylayer 15 is preferably 1 or more, and more preferably from 5 to 500.

In the case where the repeating number is less than 1, the display layeris not allowed to exhibit the structural color.

In the display member of the present invention, the structural colorobtained is not limited to a color having a peak wavelength in thevisible range. The color the structural color may have a peak wavelengthin the ultra-violet range or in the ultra-red range.

The display member exhibiting a light having a peak wavelength in theultraviolet range or in the ultra-red range may be used for a sensorincorporated in a detecting apparatus for a ultra-red light or aultra-violet light.

The particle layer distance D is preferably from 50 to 500 nm. Bysetting the particle layer distance D in the aforesaid range, theobtained structural color becomes to have a peak wavelength in the nearultra-violet, in the visible range, or in the near ultra-red range.While, when the particle layer distance D is larger than 500 nm, theobtained display layer may not exhibit a structural color.

[Spherical Bodies]

In the present invention, a spherical body is a material that forms aspherical shape in three dimensions. It is not limited to a completespherical shape but it may be an approximate spherical shape. Thematerial for the spherical body may have a state of solid, liquid or gasas long as the material has a different refractive index from that of amatrix.

The material for producing spherical bodies in the display layer 15 maybe suitably selected by considering the materials for producing thematrix M and the reflective interface forming layer 11.

To be more precise, the refractive index na of the spherical bodies isrequired to be different from the refractive index nb of the matrix M;na is required to satisfy the above-described Formula (1) in relation tothe refractive index nc of the reflective interface forming layer; andthe material for producing spherical bodies is required to be immisciblewith the material for producing the matrix M.

Further, the spherical bodies 12 composing the display layer 10 ispreferable to have a high affinity with the material for producing thematrix M.

Various substances can be cited for the spherical bodies 12 which formsthe display layer 10.

Specific examples of the substances are organic particles prepared bypolymerization of a single polymerizable monomer, or polymerization oftwo or more kinds of polymerizable monomers, which monomer includes astyrene monomer such as styrene, methyl styrene, methoxy styrene, butylstyrene, phenyl styrene, and chlorostyrene; an acrylic acid estermonomer or a methacrylic acid ester monomer such as methyl acrylate,ethyl acrylate, (iso)propyl acrylate, butyl acrylate, hexyl acrylate,octyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, butyl methacrylate, and ethylhexyl methacrylate; acarboxylic acid monomer such as acrylic acid, methacrylic acid, itaconicacid, and fumaric acid.

Further, the organic particles may be polymerized particles comprising apolymerizable monomer in which a crosslinkable monomer is added. Thecrosslinkable monomers include divinylbenzene, ethylene glycoldimethacrylate, tetraethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

Other listed examples of the substances are inorganic particles made ofinorganic oxide such as silica, titanium oxide, alumina, and copperoxide, and composite oxide; and particles formed from glass, or ceramic.

Further listed examples are core-shell type particles having coreparticles made of the aforesaid organic particles or inorganic particleseach covered with a shell made of a material different from thematerials for forming the core particles. The shell layer may be made ofmetal fine particles, metal oxide fine particles such as titania, metaloxide nano-sheet made of titania.

More listed examples of the substance are hollow type particles whichare produced by eliminating the core portion of the aforesaid core-shellparticles by applying calcination or extraction for the aforesaidcore-shell particles.

Among the aforesaid particles, the organic particles are suitably usedfor the substances for spherical bodies.

An average particle diameter of the spherical bodies 12 must be set byconsidering the relationship of a refractive index of the sphericalbodies 12 and a refractive index of the matrix M. In addition to that,the spherical bodies 12 are required to form a stable colloid solutionwhen they are dispersed. For that reason, the average particle diameterof the spherical bodies 12 is preferably from 50 to 500 nm.

By controlling the average particle diameter of the spherical bodies 12to be in the range of the aforesaid range, the dispersion thereof can bea stable colloid solution, and at the same time, the structural colorexhibited by the obtained display member will have a peak wavelength inthe range of the near ultra-violet, the visible range, or the nearultra-red.

The CV value indicating a particle distribution of the spherical bodies12 is preferably 20% or less, more preferably 10% or less, andparticularly preferably 5% or less.

When the CV value is less than 20%, the spherical body layer composed ofthe spherical bodies 12 can be regularly arranged in the matrix, and asa result, the display layer exhibiting a structural color can beprovided.

An average particle diameter can be obtained employing a scanningelectron microscope “JSM-7410” (manufactured by JEOL Ltd.) as follows:(i) to take two photographs of the spherical bodies at a magnificationof 50,000 times; (ii) to determine a maximum length by measuringarbitral 100 spherical bodies in each of the two photographs; and (iii)to calculate a number-based average value thereof. The term “the maximumlength” refers to the maximum length of lengths between any two pointson circumference of each spherical body.

Incidentally, when a picture of the spherical bodies is taken as anaggregation, the maximum length of the primary particles which forms theaggregation is measured.

The CV value is calculated by Formula (CV) below employing the standarddeviation of the number-based particle distribution and the aboveaverage particle diameter.CV value (%)=((standard deviation)/(average particlediameter))×100  Formula (CV):

The refractive index of the spherical bodies 12 can be measured usingvarious known method. The refractive index of the spherical bodies 12according to the present invention is a value obtained by the immersionmethod.

Examples of a refractive index of the spherical bodies 12 are asfollows: polystyrene 1.59, polymethyl methacrylate 1.49, polyester 1.60,fluorine modified polymethyl methacrylate 1.40, polystyrene butadienecopolymer 1.56, polymethyl acrylate 1.48, polybutyl acrylate 1.47,silica 1.45, titanium oxide (anatase type) 2.52, titanium oxide (rutiletype) 2.76, copper oxide 2.71, aluminium oxide 1.76, barium sulfate 1.64and ferric oxide 3.08.

The spherical bodies 12 which form the spherical body layer 15 may be anelement composed of a single composition, or may be a compound. Further,the aforesaid spherical bodies may be a particle on which surface asubstance, by which the spherical bodies are allowed to adhere to eachother, is adhered, or may be a particle within which a substance, bywhich particles are allowed to adhere to each other, is introduced. Byemploying such an adhesive, particles are allowed to adhere to eachother, even if the spherical bodies are made of materials which are hardto self-arrange during formation of the spherical body layer 15.Further, in the case where the spherical bodies are formed employingmaterials exhibiting a high refractive index, a material exhibiting alow refractive index may be added internally.

The spherical bodies 12 which form the spherical body layer 15 havepreferably a high degree of mono-dispersibility so as to easily achievea regular arrangement during formation of the spherical body layer 15.

To obtain spherical bodies exhibiting high mono-dispersibility, in thecase where the spherical bodies are composed of organic materials, theaforesaid spherical bodies are preferably prepared via generallycommonly used polymerization methods such as soap-free emulsionpolymerization, suspension polymerization, and emulsion polymerization.

The spherical bodies 12 may be subjected to various surface treatmentsto make the particles exhibit a high affinity to matrix M.

[Matrix]

A material for matrix M which forms the display layer 15 may be suitablyselected by considering the materials for the spherical bodies 12 andthe reflective interface forming layer 11.

To be more precise, the refractive index nb of the matrix M is requiredto be different from the refractive index na of the spherical bodies 12;nb is required to satisfy the above-described Formula (2) in relation tothe refractive index nc of the reflective interface forming layer; andthe material for producing the matrix M is required to be immisciblewith the material for producing the spherical bodies 12.

Further, the material for forming matrix M is preferable to have a highaffinity with the spherical bodies 12.

Examples of the material for forming the matrix M are: a resin which issoluble in an organic solvent; a water-soluble resin; a hydrogel; anoilgel; a photo-curable agent; a thermo-curable agent; and amoisture-curable agent.

Specific resins which are soluble in an organic solvent include apolystyrene resin, an acrylic resin, and a polyester resin.Water-soluble resins include a polyacrylic acid, a polyvinyl alcohol,and a polyvinyl chloride.

The refractive index of the matrix M can be determined by variouscommonly known methods, but the refractive index of the matrix M of thepresent invention is determined such that a thin film comprising onlythe matrix M is separately prepared and the thin film is measured usingan Abbe Refractometer.

Specific refractive indexes are, for example, 1.53 for gelatin/acaciagum, 1.51 for polyvinyl alcohol, 1.51 for sodium polyacrylate, 1.34 forfluorine modified acrylic resin, 1.51 for N-isopropyl amide, and 1.43for foamed acrylic resin.

[Preparation Method of Display Layer]

Such display layer 10 can be prepared via a method, for example, inwhich an aqueous dispersion of the spherical bodies 12, and thedispersion is applied on a surface of a surface of a substrate to allowthe spherical bodies to be self-arranged to form a periodic structure16; the formed periodic structure 16 is dried; a solution which forms amatrix M is applied on the dried periodic structure 16 so as to fill thesolution between the spherical bodies 12 then dried to be solidified;then the dried periodic structure 16 is peeled off to obtain the displaylayer 10.

Examples of the methods used for coating the aqueous dispersion of thespherical bodies 12 are such as a screen coating, a dip coating, a spincoating, a curtain coating, and a LB (Langauir-Blodgett) film formingmethod.

[Reflective Interface Forming Layer]

The material of the reflective interface forming layer 11 constitutingthe display member of the present invention is suitable selected byconsidering the materials for the spherical bodies 12 and the matrix M.

To be more precise, the refractive index nc is required to satisfy theabove-described Formula (1) in relation to the refractive index na ofthe spherical bodies 12, and also nc is requited to satisfy theabove-described Formula (2) in relation to the refractive index of thematrix M.

Specific materials for forming the reflective interface forming layer 11are, for example, a fluorinated resin, a fluorinated gel, a siliconeresin, and a silicone gel.

It may be possible to employ the reflective interface forming layer 11which is prepared by forming a hermetic sectional space by using a cellor a spacer, and then filling the space with air or a gas such ashelium.

The thickness of the reflective interface forming layer 11 may be, forexample, from 5 nm to 1 mm. When the thickness of the reflectiveinterface forming layer 11 is 5 nm or more, the reflective interfaceforming layer 11 may be hard to be peeled off or deformed during thepreparation of the display layer 10. As a consequence, total reflectionat a reflective interface S1 of the obtained display member may beeasily realized. On the other hand, when the thickness of the reflectiveinterface forming layer 11 is 1 mm or less, the color of the structuralcolor exhibited by the obtained display member may be deep.

The refractive index of the reflective interface forming layer 11 can bedetermined by various commonly known methods, but the refractive indexof the reflective interface forming layer 11 of the present invention isdetermined such that a thin film comprising only the reflectiveinterface forming layer is separately prepared and the thin film ismeasured using an refractometer.

[Display Member]

The aforesaid display member may be, for example, as is shown in FIG. 1,constructed as a sheet which is prepared by laminating a reflectiveinterface forming layer 11 and a display layer on a substrate 13.

The usable substrate 13 includes glass, ceramics, and a film or a sheetof materials such as polyethylene terephthalate (PET) and polyethylenenaphthalate (PEN). The usable substrate 13 may be black, gray or mayhave a required color according to need.

In the case where the display layer 10 is prepared using with theaqueous dispersion of the spherical bodies 12, the substrate 13 ispreferably the one having a relatively low contact angle on the surfaceagainst water. In addition to that, the substrate 13 is preferably theone having a high flatness. For these reasons, the substrate 13 may besubjected to a suitable surface treatment, and it may be subjected to ablast finishing treatment so as to obtain a condition in which thespherical bodies can be easily adhered to the surface.

The display member may be provided with a surface cover layer by theintervention of an adhesive layer on a display layer 10. The displaylayer 10 is laminated on a reflective interface forming layer 11provided on a substrate 13.

In such a display member, the substrate 13, the adhesive layer or thesurface cover layer is provided when it is needed for a required use.Moreover, the display member may have a structure to be provided with anadhesive layer for a ravel on the rear surface of the substrate 13 orthe rear surface of the reflective interface forming layer 11.

In the case where the surface cover layer is provided, the surface coverlayer may be a film made of polyethylene terephthalate (PET) andpolyethylene naphthalate (PEN), a UV curable resin, all of which exhibithigh transparency and do not prevent exhibition of a structural color inthe display layer 10.

In the case where the display member is used as a ravel, examples of theadhesives agent used for the adhesive layer for a ravel include anacrylic adhesive and an acrylic-olefin copolymer adhesive.

[Preparation Method of Display Member]

The display member of the present invention can be obtained, forexample, by laminating a display layer 10 and a reflective interfaceforming layer 11 in contact with each other.

In the aforesaid display member, the incident light entering from abovethe display layer 10 is, generally, selectively reflected at a displaylayer 10 to become a display layer selective-reflected light resultingin exhibiting a structural color. The display member of the presentinvention is provided with a specific reflective interface S1 under thedisplay layer 10. Therefore, among the light transmitted through thedisplay layer 10, the interface reflected light is selectively reflectedand the interface reflected light passes again through the display layer10. Consequently, the structural color will be produced by the combinedlights of the display layer selective-reflected light and the interfacereflected light.

Meanwhile, in the display member of the present invention, when all ofthe incident light entered in the specific reflective interface S1becomes the display layer selective-reflected light, that means, whenall of the incident light entered in the display member is totallyreflected, the observer cannot visually confirm the exhibition of thestructural color.

And, in this display member, the aforesaid interface reflected light iscontrolled by the specific property of the aforesaid specific reflectiveinterface S1. As a result, the range of observable angle which allowsthe observer to observe the exhibited structural color is suitablydetermined. Consequently, the angle dependency, in which the exhibitionof the structural color is prohibited for a large viewing angle, isrealized resulting in achieving a display member of high security.

Second Embodiment

The display member of the second embodiment of the present invention hasthe same structure as the display member of the second embodiment,except that the second embodiment uses a display layer 20, a reflectiveinterface forming upper layer 21 and a reflective interface formingunder layer 22 instead of the display layer 10 and the reflectiveinterface forming layer 11 of the first embodiment of the presentinvention.

In particular, the display member of the second embodiment has, as isshown in FIG. 3, a display layer 20 which exhibits a structural colorand a reflective interface S2 which reflects the light passing throughthe aforesaid display layer 20. The reflective interface S2 is composedof a reflective interface forming upper layer 21 and a reflectiveinterface forming under layer 22, and the under layer is provided incontact with the upper layer. When a refractive index of the matrix isnb, a refractive index of the reflective interface forming upper layeris nc1, and a refractive index of the reflective interface forming underlayer is nc2, nb, nc1 and nc2 satisfy the following Formulas (3) and(4):nb≦nc1  Formula (3)0.35<nc2/nc1<1.00.  Formula (4)

A light having an expected wavelength is selectively reflected at thereflective interface S2 when the aforesaid. Formulas (3) and (4) aresatisfied by the display member.

In such display member, a structural color is exhibited by mixed lightsof: (i) an interface reflected light which is selectively reflected atthe reflective interface S2; and (ii) a display layerselective-reflected light which is produced by the display layer 20.

And, in this display member, when the viewing angle is larger than anexpected value, the interface reflected light selectively reflected atthe reflective interface S2 is designed to become all of the lightentered in the reflective interface S2. This means the total reflectionis realized at the reflective interface S2. As a result, all of theincident light entered in the display member is reflected by either thedisplay layer 20 or the reflective interface S2. Namely, due to the factthat all of the incident light entered in the display member isreflected, exhibition of a structural color is prohibited at a viewingangle larger than an expected value.

In the display member of the present invention, the range of observableangle in which a structural color can be recognized varies depending onthe combination of the materials which form each of the matrix M, thereflective interface forming upper layer 21 and the reflective interfaceforming under layer 22. An example of a preferred range of a viewingangle is from 0 to 70°, and another example of more preferred range isfrom 0 to 55°.

An example of a range of viewing angle is as follows.

When a refractive index of a material composing a matrix M is 1.51, arefractive index of a material composing a reflective interface formingupper layer 21 is 1.51, a refractive index of a material composing areflective interface forming under layer 22 is 1.34, the range ofviewing angle is determined as 0 to 38 degree.

The ratio of the refractive indexes nc2/nc1 in the aforesaid Formula (4)indicates the conditions under which the total reflection is realized atthe interface (the reflective interface S2) between the reflectiveinterface forming upper layer 21 and a reflective interface formingunder layer 22.

When a ratio of a refractive index nc2 of the reflective interfaceforming under layer 22 to a refractive index nc1 of the reflectiveinterface forming upper layer 21, nc2/nc1 (hereafter it is called as “arefractive index ratio at a reflective interface S2”) is 0.35 or less,the range of observable angle becomes too small to view to practicaluse. On the other hand, when the refractive index ratio nc2/nc1 islarger than 1.00, the incident light entered in the reflective interfaceS2 will totally transmits through the reflective interface forming upperlayer 21 and the reflective interface forming under layer 22 resultingin failing to produce an interface reflected light. Consequently, theangle dependency for the exhibition of the structural color cannot beachieved.

The display layer 20 of the second embodiment can have the sameconstitution as the display layer of the first embodiment, except thatthe spherical bodies 12 is suitably selected by considering the materialof the matrix M, and the material of the matrix M is suitably selectedby considering the material of the reflective interface forming upperlayer 21. The substrate 13 of the second embodiment can have the sameconstitution as that of the first embodiment.

[Reflective Interface Forming Upper Layer]

The material for forming the reflective interface forming upper layer 21constituting the display member of the present invention can be suitablyselected from light transmissive materials by considering therelationship with materials for the matrix M and the reflectiveinterface forming under layer 22.

In particular, the refractive index nc1 of material is required tosatisfies the aforesaid Formula (3) with respect to the relationshipwith the refractive index nb of the matrix M, and nc1 is also requiredto satisfy satisfies the aforesaid Formula (4) with respect to therelationship with the refractive index nc2 of the reflective interfaceforming under layer 22.

Listed examples of the materials for forming the reflective interfaceforming upper layer 21 include a high refractive glass and polymethylmethacrylate (PMMA) containing Fe₃O₂.

The thickness of the reflective interface forming upper layer 21 may be,for example, from 5 nm to 1 mm. When the thickness of the reflectiveinterface forming upper layer 21 is 5 nm or more, the reflectiveinterface forming upper layer 21 may be hard to be peeled off ordeformed during the preparation of the display layer 20. As aconsequence, total reflection at a reflective interface S2 of theobtained display member may be easy to realize. On the other hand, whenthe thickness of the reflective interface forming upper layer 21 is 1 mmor less, the color density of the structural color exhibited by theobtained display member may be obtained enough.

[Reflective Interface Forming Under Layer]

The material of the reflective interface forming under layer 22constituting the display member of the present invention is suitableselected by considering the materials for the material of the reflectiveinterface forming upper layer 21.

To be more precise, the refractive index nc2 is required to satisfy theabove described Formula (4) in relation to the refractive index nc1 ofthe reflective interface forming upper layer 21.

Specific materials for forming the reflective interface forming underlayer 22 are, for example, a fluorinated resin, a fluorinated gel, asilicone resin, and a silicone gel.

It may be possible to employ the reflective interface forming underlayer 22 which is prepared by forming a hermetic sectional space byusing a cell or a spacer, and then filling the space with air or a gassuch as helium.

The thickness of the reflective interface forming under layer 22 may be,for example, from 5 nm to 1 mm. When the thickness of the reflectiveinterface forming under layer 22 is 5 nm or more, the reflectiveinterface forming under layer 22 may not be peeled off or may not bedeformed during the preparation of the display layer 20. As aconsequence, total reflection at a reflective interface S2 of theobtained display member may be easily realized. On the other hand, whenthe thickness of the reflective interface forming under layer 22 is 1 mmor less, the color of the structural color exhibited by the obtaineddisplay member may be deep.

The refractive indexes of the reflective interface forming upper layer21 and the reflective interface forming under layer 22 can be determinedby various commonly known methods. But the refractive indexes of therefractive indexes of the reflective interface forming upper layer 21and the reflective interface forming under layer 22 each are determinedsuch that thin films each comprising only the reflective interfaceforming upper layer or the reflective interface forming under layer areseparately prepared and each of the thin films is measured using an AbbeRefractometer.

The similar effects obtained by using the display member of the firstembodiment can be obtained by the aforesaid display member.

In the aforesaid display member, the incident light entering from abovethe display layer 20 is, generally, selectively reflected at a displaylayer 20 to become a display layer selective-reflected light resultingin exhibiting a structural color. The display member of the presentinvention is provided with a specific reflective interface S2 under thedisplay layer 20 and the reflective interface forming upper layer 21.Therefore, among the light transmitted through the display layer 20 andthe reflective interface forming upper layer 21, the interface reflectedlight is selectively reflected and the interface reflected light passesagain through the display layer 20 and the reflective interface formingupper layer 21. Consequently, the structural color will be produced bythe combined lights of the display layer selective-reflected light andthe interface reflected light.

Meanwhile, in the display member of the present invention, when all ofthe incident light entered in the specific reflective interface S2becomes the display layer selective-reflected light, that means, whenall of the incident light entered in the display member is totallyreflected, the observer cannot visually confirm the exhibition of thestructural color.

And, in this display member, the aforesaid interface reflected light iscontrolled by the specific property of the aforesaid specific reflectiveinterface S2. As a result, the range of observable angle which allowsthe observer to observe the exhibited structural color is suitablydetermined. Consequently, the angle dependency, in which the exhibitionof the structural color is prohibited for a large viewing angle, isrealized resulting in achieving a display member of high security.

In the foregoing embodiments, the present invention was specificallydescribed, but the embodiments of the present invention are not limitedto the above, and the embodiments can be variously modified.

EXAMPLES

The present invention is described below with reference to examples, butthe present invention is not limited to them. In the followings, themeasurement of an average particle diameter, a CV value and a refractiveindex are carried out as described above.

[Preparation of Spherical Body Dispersion 1]

71 parts by mass of styrene (St), 20 parts by mass of n-butyl acrylate(BA) and 9 parts by mass of methacrylic acid (MAA) were heated at 80° C.to obtain a mixed solution of monomers. The surfactant solution, inwhich 0.4 parts by mass of sodium dodecyl sulfonate was dissolved into263 parts by mass of distilled water, was heated to 80° C., whichsurfactant solution was then blended with the above mixed solution ofmonomers. After that, the resulting mixture was subjected to adispersion treatment for 30 minutes via a mechanical dispersionapparatus “CLEARMIX” (produced by M Technique Co., Ltd.) to prepare anemulsified dispersion.

Into a reaction vessel equipped with a mixer, a heating and coolingapparatus, a nitrogen charging apparatus, and a material—additiveintroducing apparatus, the above-described emulsified dispersion and asurfactant solution which was prepared by dissolving 0.09 parts by massof sodium dodecyl sulfonate into 142 parts by mass of distilled water,was introduced, and the temperature of the solution was raised to 80° C.while stirring at a stirring rate of 200 rpm in a nitrogen gas streamatmosphere. Into the above solution, 1.4 parts by mass of potassiumpersulfate, and 54 parts by mass of water were introduced, and theresulting solution was subjected to polymerization treatment for 3hours. A dispersion of spherical bodies was produced by the abovepolymerization reaction. Then the dispersion of spherical bodies wasloaded to a centrifuge so as to eliminate large sized particles andsmall sized particles. A dispersion of spherical bodies containingspherical bodies having a high mono-dispersibility [1] was produced bythis procedure (hereafter, it is called as “a spherical bodydispersion”). The spherical bodies [1] in the spherical body dispersion[1] have an average particle diameter of 280 nm, a CV value of 2.8 and arefractive index of 1.56.

[Preparation of Spherical Body Dispersion 2]

A mixed solution was prepared with 4.7 parts by mass of methanol, 12.6parts by mass of pure water and 3.0 parts by mass of ammonia. Theprepared mixed solution was introduced into a reaction vessel equippedwith a mixer and a material—additive introducing apparatus, then 22. 8parts by mass of silicone methoxide was dropwise added while stirringthe mixture at 20° C. and hydrolysis reaction was carried out. By thisprocedure, a spherical body dispersion [2] containing spherical bodieshaving a high mono-dispersibility was produced. The spherical bodies [2]in the spherical body dispersion [2] have an average particle diameterof 240 nm, a CV value of 5.2 and a refractive index of 1.45.

[Preparation of Spherical Body Dispersion 3]

A mixture of 90 parts by mass of toluene, 10 parts by mass ofpolymethacrylic acid (PMAA) and 9.0 parts by mass of Fe₂O₃ was subjectedto a dispersion treatment for 30 minutes via a mechanical dispersionapparatus “CLEARMIX” (produced by M Technique Co., Ltd.) to prepare adispersion of PMMA/Fe₂O₃. This dispersion was mixed with a surfactantsolution which was prepared by dissolving 0.4 parts by mass of sodiumdodecyl sulfonate into 400 parts by mass of distilled water. Then, theresulting mixture was subjected to a dispersion treatment for 30 minutesvia a mechanical dispersion apparatus “CLEARMIX” (produced by MTechnique Co., Ltd.) to prepare an emulsified dispersion. The obtainedemulsified dispersion was heated at 60° C. at a reduced pressure toevaporate toluene resulting in a dispersion of minute sphericalparticles made of a PMMA resin in which Fe₂O₃ is dispersed. Thusobtained dispersion minute spherical particles were loaded to acentrifuge so as to eliminate large sized particles and small sizedparticles. A spherical body dispersion [3] containing spherical bodies[3] having a high mono-dispersibility was produced by this procedure.The spherical bodies [3] in the spherical body dispersion [3] have anaverage particle diameter of 150 nm, a CV value of 8.4 and a refractiveindex of 2.87.[Preparation of Spherical Body Dispersion 4]

20 parts by mass of titanium oxide prepared by a titanium alkoxidemethod (of rutile type, having an average particle diameter: 150 nm, aCV value: 8.4 and a refractive index: 2.76) was dispersed in asurfactant solution which was prepared by dissolving 0.02 parts by massof sodium dodecyl sulfonate into 100 parts by mass of ion-exchangedwater. By this procedure, a spherical body dispersion [4] containingspherical bodies [4] was produced.

Example 1 Preparation of Display Member [1]

The spherical body dispersion [1] thus prepared was applied using a barcoating method on a cleaned glass plate and then dried to obtain aperiodic structure having a thickness of 20 μm. Then a silicone gelcoating solution was applied on the periodic structure and the coatingsolution was impregnate between the spherical bodies. Then, theimpregnated solution was heated at 60° C. for 1 hour so as to solidifythe impregnated solution resulting in forming a display layer [1]. Theformed display layer [1] was peeled from the glass plate. The refractiveindex of the matrix of the silicone gel is shown in Table 1.

On the other hand, a fluorinated gel coating solution was applied on ablack colored polyethylene terephthalate (PET) film and the applied gelcoating solution was heated 60° C. for 1 hour resulting in forming afluorinated gel film having a thickness of 10 μm. The refractive indexof the reflective interface forming layer composed of the fluorinatedgel layer is shown in Table 1.

A display member [1] in sheet form was prepared by laminating thedisplay layer [1] on the fluorinated gel layer.

The prepared display member [1] was visually observed from the frontdirection perpendicular to the display member [1] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was red.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [1] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 52 degree. It was confirmed that only a black color wasobserved at a viewing angle θ of from 53 to 90 degree. These results areshown in Table 2. These results show that the display member [1] has anangle dependency by which the exhibition of the structural color wasprevented depending on a viewing angle.

Example 2 Preparation of Display Member [2]

A fluorinated gel coating solution was applied on a black coloredpolyethylene terephthalate (PET) film to obtain a coating layer of thefluorinated gel coating solution. A cleaned glass plate was laminated onthe coating layer of the fluorinated gel coating solution, then thespherical body dispersion [2] was applied using a bar coating method onthe cleaned glass plate and then dried to obtain a periodic structurehaving a thickness of 20 μm. Then an aqueous solution containing 20weight % of polyvinylalcohol was coated on the periodic structure toimpregnate the aqueous solution between the spherical bodies. Then, theimpregnated solution was heated at 110° C. for 1 hour so as to solidifythe impregnated solution resulting in forming a display layer [2].Further, a transparent PET film having a thickness of 5 μm was adheredto display layer [2] so as to prepare a display member [2] in sheetform. The refractive index of the matrix of polyvinyl alcohol is shownin Table 1. The refractive index of the reflective interface formingupper layer made of glass and the reflective interface forming underlayer made of the fluorinated resin coated layer are shown in Table 1.

The prepared display member [2] was visually observed from the frontdirection perpendicular to the display member [2] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was yellow.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [2] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 38 degree. It was confirmed that only a black color wasobserved at a viewing angle θ of from 39 to 90 degree. These results areshown in Table 2.

These results show that the display member [2] has an angle dependencyby which the exhibition of the structural color was prevented dependingon a viewing angle.

Example 3 Preparation of Display Member (3)

An ethanol dispersion containing 1 weight % of PMMA particles having ahigh mono-dispersibility and having an average particle diameter of 2 μmwas sprayed on a black colored polyethylene terephthalate (PET) film toadhere the PMMA particles. Then, a cleaned glass plate having a highrefractive index was laminated on the PET film so as to form an airlayer between the PET film and the high refractive glass plate. Then,the spherical body dispersion [3] was applied using a bar coating methodon the high refractive glass plate and was dried to obtain a periodicstructure having a thickness of 20 μm. Then a toluene solutioncontaining 20 weight % of polyester and titanium oxide (the amount ofwhich is 20 weight % based on the weight of the polyester) was coated onthe periodic structure to impregnate the toluene solution between thespherical bodies. Then, the impregnated solution was heated at 60° C.for 1 hour to eliminate toluene and to solidify the impregnated solutionresulting in forming a display layer [3]. Further, a UV curable resinsolution was coated on the display layer [3] and irradiated with a UVlamp for 30 seconds to obtain a protective layer. By this procedure, adisplay member in sheet form was prepared. The refractive index of thematrix of polyester containing titanium oxide is shown in Table 1. Therefractive index of the reflective interface forming upper layer made ofmade of the high refractive glass and the reflective interface formingunder layer made of the air layer are shown in Table 1.

The prepared display member [3] was visually observed from the frontdirection perpendicular to the display member [3] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was red.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [3] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 21 degree. It was confirmed that only a black color wasobserved at a viewing angle θ of from 22 to 90 degree. These results areshown in Table 2.

These results show that the display member [3] has an angle dependencyby which the exhibition of the structural color was prevented dependingon a viewing angle.

Example 4 Preparation of Display Member [4]

A fluorinated resin solution was applied on a black colored polyethyleneterephthalate (PET) film and was heated at 10° C. for 30 minutes tosolidify the coated solution resulting in forming a fluorinated resinlayer. A toluene dispersion containing 5.5 weight % of PMMA and Fe₃O₂(the amount of which is 1000 weight % based on the weight of PMMA) wascoated on the fluorinated resin layer and was dried resulting in aFe₃O₂/PMMA layer having a thickness of 5 μm. Then, the spherical bodydispersion [4] was applied using a bar coating method on theFe₃O₂/PMMA-layer and was dried to obtain a periodic structure having athickness of 20 μm. Further, a polyester resin powder was applied on theperiodic structure and was heated at 100° C. for 30 minutes so as toimpregnate between the spherical bodies and then was solidifiedresulting in forming the display layer [4]. Further, a transparent PETfilm having a thickness of 5 μm was adhered to display layer [4] so asto prepare a display member [4] in sheet form. The refractive index ofthe matrix made of the polyester powder is shown in Table 1. Therefractive index of the reflective interface forming upper layer made ofthe Fe₃O₂/PMMA layer and the reflective interface forming under layermade of the fluorinated resin layer are shown in Table 1.

The prepared display member [4] was visually observed from the frontdirection perpendicular to the display member [4] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was yellow.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [4] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 26 degree. It was confirmed that only a black color wasobserved at a viewing angle θ of from 27 to 90 degree. These results areshown in Table 2.

These results show that the display member [3] has an angle dependencyby which the exhibition of the structural color was prevented dependingon a viewing angle.

Comparative Example 1 Preparation of Display Member [5]

A display member [5] in sheet form was prepared in the same manner aspreparation method for the display member [1] in Example 1 except thatthe fluorinated gel layer (reflective interface forming layer) was notprovided for the display member [5].

The prepared display member [5] was visually observed from the frontdirection perpendicular to the display member [5] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was red.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [5] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 90 degree. The result is shown in Table 2.

This result shows that the comparative display member [5] exhibits astructural color regardless of the viewing angle.

Comparative Example 2 Preparation of Display Member [6]

A display member [6] in sheet form was prepared in the same manner aspreparation method for the display member [2] in Example 2 except thatthe reflective interface forming under layer made of the fluorinatedresin coated layer was not provided for the display member [6].

The prepared display member [6] was visually observed from the frontdirection perpendicular to the display member [6] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was yellow.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [6] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 90 degree. The result is shown in Table 2.

This result shows that the comparative display member [6] exhibits astructural color regardless of the viewing angle.

Comparative Example 3 Preparation of Display Member [7]

A display member [7] in sheet form was prepared in the same manner aspreparation method for the display member [1] in Example 1 except that apolyester resin was used instead of the fluorinated gel layer.

The prepared display member [7] was visually observed from the frontdirection perpendicular to the display member [5] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was green.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [7] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 90 degree. The result is shown in Table 2.

This result shows that the comparative display member [7] exhibits astructural color regardless of the viewing angle.

Comparative Example 4 Preparation of Display Member [8]

A display member [8] in sheet form was prepared in the same manner aspreparation method for the display member [3] in Example 3 except that aPMMA plate containing arsenic selenide was used instead of the highrefractive glass.

The prepared display member [8] was visually observed from the frontdirection perpendicular to the display member [8] (the viewing angleθ=0, which is determined as an angle of viewing direction with respectto a perpendicular line of the display layer). The color of theexhibited structural color was red.

(Evaluation of the Visibility for the Structural Color)

The prepared display member [8] was visually observed by increasing theviewing angle θ by 1 degree at a time. It was confirmed that theexhibition of the structural color was observed at a viewing angle θ offrom 0 to 16 degree. It was confirmed that only a black color wasobserved at a viewing angle θ of from 17 to 90 degree. The result isshown in Table 2.

This result shows that the comparative display member [8] exhibits astructural color regardless of the viewing angle.

TABLE 1 Reflective Reflective Reflective Interface Interface InterfaceForming Spherical Forming Forming Upper Under bodies Matrix Layer LayerLayer Embodiment Kind na Kind nb Kind nc Kind nc1 Kind nc2 nc/na nc/nbnc2/nc1 ** 1 First PSt/BA/MAA 1.56 *1 1.41 *2 1.34 — — — — 0.859 0.950 —2 Second SiO₂ 1.45 PVA 1.51 — — Glass 1.51 *3 1.34 — — 0.887 3 SecondFe₂O₃/PMMA 2.87 TiO₂/PEs 1.80 — — High 2.58 Air 1.00 — — 0.388Refractive Glass 4 Second TiO₂ 2.76 PEs 1.60 — — Fe₂O₃/PMMA 2.91 *3 1.34— — 0.460 Comp. 1 — PSt/BA/MAA 1.56 *1 1.41 — — — — — — — — — 2 FirstSiO₂ 1.45 PVA 1.51 Glass 1.51 — — — — 1.041 1.000 — 3 First PSt/BA/MAA1.56 TiO₂/PEs 1.41 PEs 1.80 — — — — 1.026 1.277 — 4 Second Fe₂O₃/PMMA2.87 PEs 1.80 — — As₂Se₃/PMMA 3.13 Air 1.00 — — 0.319 **: Example,Comp.: Comparative Example, *1: Silicone Gel, *2: Fluorinated Gel *3:Fluorinated Resin

TABLE 2 Evaluation Result Viewing Angle Example 1 0-52° C. 2 0-38° C. 30-21° C. 4 0-26° C. Comparative 1 0-90° C. Example 2 0-90° C. 3 0-90° C.4 0-16° C.

The display member of the present invention can be used for a displayhaving a high level of security.

1. A display member comprising: a display layer which exhibits astructural color and contains therein spherical bodies and a matrix; anda reflective interface which reflects a light transmitted through thedisplay layer, wherein the reflective interface is made between thedisplay layer and a reflective interface forming layer which is providedin contact with the display layer; a refractive index, na, of thespherical bodies, a refractive index, nb, of the matrix, and arefractive index, nc, of the reflective interface forming layer satisfythe following Formulas (1) and (2):0.35<nc/na<1.00  Formula (1)0.35<nc/nb<1.00; and  Formula (2) the spherical bodies are regularlyarranged in a periodic structure both in a plane direction and in adepth direction of the display layer.
 2. The display member of claim 1,wherein an absolute value of a difference between a refractive index ofthe spherical bodies and that of the matrix is from 0.02 to 2.0.
 3. Thedisplay member of claim 1, wherein the display layer has a thickness of0.1 to 100 μm.
 4. The display member of claim 1, wherein the displaylayer contains a spherical body layer having a thickness of 0.1 to 100μm.
 5. The display member of claim 4, wherein the spherical body layerhas a repeating number of 5 to
 500. 6. The display member of claim 5,wherein a particle layer distance in the display layer is from 50 to 500nm.
 7. The display member of claim 1, wherein the spherical bodies arearranged in a state of contact with each other.
 8. A display membercomprising: a display layer which exhibits a structural color andcontains therein spherical bodies and a matrix; and a reflectiveinterface which reflects a light transmitted through the display layer,wherein the reflective interface is made between a reflective interfaceforming upper layer and a reflective interface forming under layer,provided that the reflective interface forming upper layer is located ina position nearer to the display layer than the reflective interfaceforming under layer, and the under layer is provided in contact with theupper layer; and a refractive index, nb, of the matrix, a refractiveindex, nc1, of the reflective interface forming upper layers and arefractive index, nc2, of the reflective interface forming under layersatisfy the following Formulas (3) and (4):nb≦nc1  Formula (3)0.35<nc2/nc1<1.00; and  Formula (4) the spherical bodies are regularlyarranged in a periodic structure both in a plane direction and in adepth direction of the display layer.
 9. The display member of claim 8,wherein an absolute value of a difference between a refractive index ofthe spherical bodies and that of the matrix is from 0.02 to 2.0.
 10. Thedisplay member of claim 8, wherein the display layer has a thickness of0.1 to 100 μm.
 11. The display member of claim 8, wherein the displaylayer contains a spherical body layer having a thickness of 0.1 to 100μm.
 12. The display member of claim 11, wherein the spherical body layerhas a repeating number of 5 to
 500. 13. The display member of claim 12,wherein a particle layer distance in the display layer is from 50 to 500nm.